The present invention relates to a prism optical system that uses a rotationally asymmetric surface, an image display apparatus that incorporates a prism optical system, and an imaging apparatus that incorporates a prism optical system.
A prism optical system known so far in the art is typically a prism that includes a plurality of optical surfaces, and in the form of an optical system adapted to view an image display device, light emanating from the display device enters the prism for internal reflection, and exits out of the prism, arriving at the eyeballs of a viewer where an image is viewed as an enlarged virtual image. For prior arts concerning this, for instance, there is the mention of JP(A) 2008-076429 showing a prism wherein a first-order image is formed by at least three reflecting surfaces for projection onto the eyeballs, and JP(A) 2008-076429, JP(A) 2007-094175 and JP(A) 2004-325985 teaching that a hologram element is located at a lens site of eyeglasses.
Another conventional prism optical system includes a parallelogram prism wherein light is reflected a plurality of times and guided in front of the eyeballs of a viewer for projection through an eyepiece onto the eyeballs, or a light guide and an eyepiece for projection of light onto the eyeballs (see JP(A) 2001-264681 or JP(A) 2006-003879). Besides, it is proposed to make use of a prism including a combination of mutually decentered five optical surfaces to project an image from an image display device onto the eyeballs of a viewer (see Patent Publication JP(A) 2012-027350).